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  4. Light of wavelength 488 nm is produced by an Argon laser which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photo electrons is 0.38 V. Find the work function of the material form which the emitter is made.

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Q. Light of wavelength 488 nm is produced by an Argon laser which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photo electrons is 0.38 V. Find the work function of the material form which the emitter is made.

NTA AbhyasNTA Abhyas 2020

Solution:

$E=\frac{h c}{\lambda }=\frac{1242 eV}{488}=2.55 \, eV$
$K_{m a x}=eV_{0}=e\times 0.38=0.38 \, eV$
$K_{m a x}=\frac{h c}{\lambda }-\phi_{0}=E-\phi_{0}$
$\phi_{0}=E-K_{m a x}=\left(2 .55 - 0 .38\right)=2.17 \, eV$